The present invention relates generally to a tool for bending sheet metal and more particularly to a tool for hemming architectural sheet metal roof panels.
In the construction industry and particularly the roofing industry, it has become customary to install sheet metal panels on the roofs of certain buildings. These panels have become very popular insofar as their ease of installation and the protection they provide against the elements. Moreover, when properly installed, the metal panels add greatly to the aesthetic appearance of the building.
The typical panel is elongate and includes a flat portion with opposed side walls attached thereto which extend orthogonally away therefrom. A flange is attached to the flat portion and defines a leading edge. When installed, each panel lies adjacent one another with a side wall of each joined to a side wall of an adjacent panel by a U-shaped panel clip which fits around a portion of both sidewalls and is anchored to the roof by two flange extensions.
The flange defining the leading edge of the panel is usually given a 180.degree. U-shaped bend wherein such bend defines an elongate recess. A joggle cleat installed on the roof includes a flat edge portion which is received in the recess defined by the bent flange portion on the panel. More specifically, when the joggle cleat is installed on the roof, a first portion is fastened to the roof. The flat edge extends away from the first portion and is separated from the roof by a small space. The 180.degree. bend in the panel's flange is designed to receive the flat edge of the joggle cleat. Thereafter, successive panels may be secured to one another by the aforementioned panel clip.
The 180.degree. bend in the flange defining the panel's leading edge is a standard feature in sheet metal roof panels. That is, it is customary to form such a bend or hook as it is sometimes called, before installing the panels on the roof. Heretofore in the industry, such bending has been accomplished via simple handheld bending tools such as pliers or crimping tools. These tools require varying degrees of skill and effort by the workman, depending on the thickness of the material used and the panel width.
Typically, a worker will physically clamp or grip the flange defining the leading edge with the tool and turn it under to form the bend. Consistent problems attendant with the use of these tools is that uniform bends depend upon the skill of the individual workman. Moreover, the process of applying such bends to the leading edge flange of the panel usually requires two workmen, one to hold the panel and the other to use the bending tool. During such operation, tearing fractures often occur in the panel's flange due to unevenly applied stresses. Further, panels must often be inverted to perform the bending operation and then turned back over for installation which can be cumbersome with longer roof panels. Needless to say, this whole process is very time consuming and can end up costing the builder and hence the owner a great deal of money.
Although a number of devices for bending sheet metal are known, such devices are limited in utility because they either fail to provide a means for securing the workpiece during the bending operation or they do not provide a 180.degree. bend in the flange portion. One such device is disclosed in U.S. Pat. No. 4,191,043, entitled "METAL DUCT DRIVE BENDING TOOL, " issued to Schaffer. Schaffer discloses a triangularly shaped duct bending tool having a handle and a support member. The handle is connected via a hinge to the support member and includes a slot into which a piece of sheet metal fits for subsequent bending. Plural teeth are provided on the handle to exert bending pressure on the sheet metal when the handle and support member are separated and used to bend the metal. Schaffer does not disclose the use of any structure to confine the workpiece or sheet metal to the slot during the bending thereof. Rather, the user must physically bias the tool against the workpiece when bending it. Moreover, although the tool allows for a 180.degree. bend in the metal, its utility is severely limited by the gauge of the metal sought to be bent. For instance, the tool disclosed in Schaffer would be ineffective in bending a workpiece consisting of a thicker gauge metal because the user must directly physically bend the workpiece with the tool. Schaffer provides no means for the user to leverage their strength and bend thicker gauge metals. Furthermore, the bending of the metal workpiece is necessarily complicated by the fact that the user must ensure that the sheet metal stays within the slot during the bending operation by physically biasing the tool against the workpiece. On longer workpieces, this would necessarily require two people.
Thus, significant problems with the prior art metal bending tools are that generally, more than one person is required to operate the tool. This is especially so when the workpiece is longer such as a roof panel. Another problem with the prior art metal bending tools of the type which may be operated by one person is that such tools are necessarily limited in utility by the gauge or thickness of the metal sought to be bent. The thicker the sheet metal, the less likely that one person is going to be able to physically bend it. Moreover, uniform bends and stress tears in the metal are all problems which the prior art fails to fully solve.
With the above problems in mind, it is a general object of the invention to provide a tool for bending sheet metal which can operated by one person without regard to the gauge or thickness of metal sought to be bent.
It is another object of the invention to provide a tool for bending sheet metal which provides a means for holding the sheet metal in place during the bending operation.
It is a further object of the invention to provide a tool for bending sheet metal which reduces the chance of stress tears due to non-uniform bending.
It is yet another object of the invention to provide a tool for bending sheet metal which is small and portable and which may be used at a variety of sites.
It is yet a further object of the invention to provide a tool for bending sheet metal which is inexpensive to manufacture, easy to use and reduces the skill necessary to operate it.
In brief summary, the invention achieves these and other objects in the form of a sheet metal bending tool for use in bending an end portion of a piece of sheet metal which tool includes a base defining a sheet metal work area into which a workpiece may be inserted, a confronting member mounted on the base adjacent the work area and reciprocally movable relative to the base for biasing or pressing a portion of the workpiece against the base to fix its position, and a bending member rotatably mounted to the base and spaced from the confronting member for bending an end portion of the sheet metal. In the preferred embodiment, an elongate slot is provided on the bending member for receiving an end portion of the workpiece and thereafter allowing for the uniform bending of the portion. Structure within the slot allows for the overbending or overbreaking of the end portion to counter the workpiece's inherent resiliency. The slot is adjustable for accommodating metals of differing gauges or thicknesses. The bending member is also provided with a ratcheting feature which allows for reciprocal incremental bending of the workpiece. A method for accomplishing the same is also described.
These and other objects and advantages of the invention will become more fully apparent when the detailed description below is read with reference to the accompanying drawings.